Objective This Paper is to explore the application value of CT perfusion imaging and differential value of measured CT value in the diagnosis of acute cerebral infarction. Methods Thirty six patients with acute cerebral infarction admitted the Radiology Department of the Hospital were selected as research subjects, retrospective analysis and summary were conducted according to clinical data. CT plaint scan and brain CT perfusion imaging were made respectively, The time to peak (TIP), cerebral blood flow (CBF) and cerebral blood volume (CBV) of CT perfusion imaging were evaluated, the difference of CT value on both sides of symmetric positions was measured. In addition, 36 patients with no brain disease and normal nervous function were divided into the control group, and diagnostic value of the difference between CT perfusion imaging and CT measurement value in acute cerebral infarction was analyzed. Results It is visually found that there were 17 patients with suspicious lesions with the sensitivity at 47.2%, and it was found that there were 28 patients with suspicious lesions by measuring CT value difference. It was found that the CTP of 3 patients was normal CT perfusion imaging examination, and such 2 patients were finally diagnosed to suffer from transient ischemic attack, and others were abnomal, rCBF, rCBV and rTTP changed obviously, the comparison in lesion center and perimeter and controlled side satisfied p<0.05, and the differences were statistically significant. Conclusion CT perfusion imaging and the difference value in CT value measurement delivers high application value in the diagnosis of acute cerebral infarction, and it is capable of diagnosing cerebral infarction in early differential diagnosis, the infarct area and ischemic penumbra area may be differentiated via through quantitative analysis, providing important basis for clinical determination on the existence of infarct and development of therapeutic schedule.